1. Field of the Invention
The invention is related to adjustment and assembly of parts in an automotive axle assembly. More particularly, the invention is an offset pinion shaft and gear in a differential axle assembly featuring simple adjustment capabilities to control the relative position of the pinion gear and ring gear.
2. Description of Related Art
Automotive manufacturers are concerned with the problem of axle gear noise and are seeking ways to insure a quite gear mesh. Without a means to adjust relative pinion gear position within a differential axle assembly, the gear noise is dependent upon the machining accuracy of the carrier housing of the ring gear and pinion gear. The offset position is critical to quite operation of the gear set and is often beyond the machining capability of the carrier housing. Adjustability of the offset position offers a much-needed solution to the noise problem and is presented herein by the present invention.
In prior art axle designs, the pinion gear position is not readily adjustable and the resulting pinion gear to ring gear offset is difficult to maintain with precision. Even by employing great care and expense during machining of the carrier housings, a significant offset error exists, and when the carrier housing does not match the desired gear offset precisely, the gear mesh will produce noise during operation.
Accordingly, it is an object of the invention to provide a means for adjusting pinion gear position in a differential axle assembly.
It is another object of the invention to achieve an optimal gear mesh between a pinion gear and ring gear in an axle assembly thereby reducing gear set noise during operation.
It is a further object of the invention to utilize a two-piece carrier housing for a differential axle assembly to allow for adjustability of a pinion assembly relative to a differential housing.
It is another object of the invention to provide an eccentric pilot for the pinion assembly such that rotation of the pinion assembly adjusts pinion gear offset.
A specific object of the invention is to allow for lateral and axial adjustment of the pinion assembly relative to the differential housing.
It is a further object of the invention to achieve quiet operation of a gear set in a differential axle assembly.
The invention is a differential axle assembly having an adjustable gear mesh. The assembly includes a differential housing, a ring gear rotatably mounted within the differential housing, and a pinion assembly having a pinion gear driving the ring gear during operation of the differential axle assembly. The pinion assembly is eccentrically mounted within a bore of the differential housing such that the gear mesh between the pinion gear and the ring gear is adjustable by rotation of the pinion assembly within the bore.
The invention also provides a device for positioning the pinion assembly in an axial direction with respect to an axis of rotation of the pinion gear and to a centerline of the bore. This device includes at least one shim mounted between the differential housing and the pinion assembly.
The differential axle assembly according to the invention can have a pinion assembly which is offset relative to the ring gear, or a pinion assembly that has a theoretical offset of zero relative to the ring gear.
The pinion assembly according to the invention includes a pinion carrier having an inner bearing and an outer bearing bore with concentric centerlines. The pinion carrier has an outer circumferential surface with an eccentric centerline relative to the inner and outer bearing bore centerlines. The inner and outer pinion bearings are seated within the inner and outer bearing bores respectively. The pinion shaft is supported for rotation by the inner and outer pinion bearings such that an axis of rotation of the pinion shaft is aligned with the centerlines of the inner and outer bearing bores. However, the pinion shaft is eccentric with respect to the centerline of the outer circumferential surface of the pinion carrier. The outer circumferential surface of the pinion carrier is mounted within the bore of the differential housing.
The invention provides for a differential axle assembly with an adjustable offset between a ring gear and a pinion gear. The axle assembly includes a differential housing supporting a differential case including the ring gear and differential gearing. The differential case is supported by the differential housing for rotation on a pair of roller bearings. A pinion assembly carrier supports a pinion gear and pinion shaft for rotation on a pair of roller bearings. The pinion assembly is mounted eccentrically within a bore of the differential housing such that rotation of the pinion carrier within the bore adjusts the offset between the ring gear and the pinion gear.
The differential housing and the pinion assembly are joined at a bolted flange joint. The bolted flange joint includes a circumferential differential housing flange surrounding the bore in the differential housing. The circumferential differential housing flange has threaded holes to receive screws. A circumferential pinion carrier flange surrounds the pinion carrier. The pinion circumferential carrier flange has mounting slots for the screws to pass through and the mounting slots are circumferentially extended along the pinion circumferential carrier flange to enable rotational adjustment of the pinion carrier relative to the differential housing. Upon a completed rotational adjustment of the pinion assembly relative to the differential housing, the screws are tightened to maintain the desired position.